Wednesday, April 13, 2016

Monogenesis, polygenesis, and militant agnosticism

When playing the cognate hunting game or the etymology identification game in
historical linguistics, there are many different rules that one needs to keep
in mind. Words that look similar are not necessarily related — they could be
simple look-alikes (Trask 2000:202). If words are too similar, they could be borrowings. If we quote colleague
X from the camp of linguists believing in theory t₁ we should make sure
that we also quote colleague Y from the camp of linguists believing in the
theory t₂, especially if we do not know the peer reviewers, etc.

A particularly
important rule that is often surprising for biologists is the rule that says we can only compare languages that we know are related. We
could, of course, compare all languages in the world (and people do compare all
languages in the world), but the point is that we are not allowed to compare languages
historically unless we know whether they share a common origin. This rule is
reflected in a long-standing debate regarding the question of how we can
prove that two languages are related. Here, we have basically two opposing
camps, one claiming that only grammar can prove language relationship, and one
claiming that only the lexicon is suitable for that task (Dybo and
Starostin 2008, Campbell and Poser 2008).

That we have to prove that two or more languages are related before we can
start to compare them is in strong contrast to biology. The idea of multiple origins as an alternative to a single origin itself has also been discussed in evolutionary
biology (David has shown this in an earlier blogpost dealing with networks with multiple roots). In linguistics, however, we are largely agnostic regarding the common origin of
all languages, and the degree of agnosticism may go even so far that it acquires a
missionary zeal. Attempts to explain how language evolved, that is, how
language originated as a means for communication, always run the danger of
being ridiculed by the linguistic community. Under very bad circumstances, they
can even cast a very dark shadow on the linguistic reputation of those who
proposed them.

Affirming our disinterest in the origin of language has a long tradition.
In its Statuts from 1866 (published in 1871), the
Société de Linguistique de Paris declared that it would not support any
research on the origin of language. Even August Schleicher, the father of the
language tree, affirmed this attitude in a letter to Ernst
Haeckel (Schleicher 1863: 22), where he wrote:

It is impossible to presuppose a material descent of all languages from a single proto-language. (My translation, original text: "Eine so zu sagen materielle Abstammung aller Sprachen von einer einzigen Ursprache können wir also unmöglich voraussetzen.")

Although it is not
explicitly spelled out nowadays, these statutes are still active in most
linguistic institutes.

Being agnostic about the origin of language means that we cannot exclude the
possibility that two languages, like, say, Chinese and English, are ultimately
not related at all. And if they are ultimately not related, it would be futile
to compare them with the hope to find linguistic material that goes back to
their common ancestor. Biologists, who usually take the Tree of Life for
granted (albeit a bush in the end), might ask themselves for the reasoning behind this agnosticism in linguistics. The reasons are rather simple to state: If we
make the very conservative assumption, based on archeological records, that
human language originated about 100,000 years ago (Dediu and Levinson
2013), and contrast it with the first written records of
languages (about 5,000 years ago), and the presumed time depths of our current
comparative method (Meillet 1925, Weiss
2014), which optimistically allows us to reach out 10,000
years back in time, we simply do not have the means to make any qualified
linguistic hypothesis regarding the origin of all those 7,000 and more
languages spoken today (count based on Hammarström et al. 2015).

The reasons why linguists prefer to maintain an agnostic attitude are
completely comprehensible for me. Whether it is good to be agnostic, is
another question. And whether it is good to be as militant as are some linguists regarding the question of language origin is yet another one. For the
context of evolutionary biology, for example, a little bit of agnosticism
regarding the Tree of Life might bring up interesting dynamics. The same could
be said about a little bit of "faith" in linguistics, be it that one believes
that language originated independently in multiple places at the same or
different times, or be it that one supports a monophyletic origin of a
"Language of Eden". Neither of the theories has immediate impact on the way
we pursue our historical comparison of languages. Even under a monogenesis
assumption we would still need to prove a close affinity between languages
before we could start comparing them with our traditional methods.

In the long
run, however, it might help us to get some of the tension out of our
long-standing debates. If we took monogenesis for granted, for example, people
would be less afraid of comparing random pairs of languages, and in the long
run we could gain new insights into distant relationships. If we rejected
monogenesis, on the other hand, we could try to identify how many times language
originated independently.

It is (and here you see my own agnostic attitude) not really important whether we stick to monogenesis or polygenesis in the end. What is important is that we are clear about the consequences that either of these two theories might have on our research in the future. Agnosticism is a useful attitude as long as it does not prevent us from asking questions. Following up on David's earlier blogpost,
it seems clear to me that especially linguists might profit a lot
from rooted network approaches that allow for multiple roots, since it would allow us to keep our agnosticism without suppressing our curiosity.